The Tesla test drive is very low pressure... it is more about education.
This ^^ was also my experience. Very low pressure, very pleasant experience overall. Never once did they question whether I was serious about buying a Model S or if I could afford one.
Do they come with you or let you drive it alone? anyone gotten one for longer than the lets say 20 mins? how long you get? anyone gotten an overnight? I have seen some dealers do that, with lower end cars though.
In my case, I took 2 test drives before buying a Model S. My first test drive the Tesla Owner Advisor came with me. Test drive was about 1/2hr total, but about 10min was the OA explaining things inside the car and the UI, and part of the remaining time taken up by the OA just driving the car away from the bumper-to-bumper city center streets to a more isolated access road down by the waterfront. Honestly the first test drive was disappointingly short. I did not buy a Model S immediately after that test drive, but I kept in touch with the OA frequently by email and he was very good at answering my many questions.
One of my big concerns about the MS was whether or not it would fit into my small garage - it's a much larger car than my current car - so early on he offered an overnight test drive/garage fit. For various reasons I couldn't take up his offer until almost 3 months later, but during our ongoing communications those few months he kept the offer of an overnight drive open. When I finally took the 2nd, overnight test drive, I was given the car to take home on my own from about 5pm until 10am the next morning (when the store opened). So basically I think they let you do an overnight test drive during off-hours, with a car that would normally be used for the "regular" 1/2 test drives during business hours.
I was able to drive the model I was interested in (70D, both test drives), and coincidentally the 7.0 firmware came out just days before my 2nd test drive so I was able to try Autopilot even though I was not originally interested in it (however, that 2nd test drive convinced me to change my mind and buy the AP). The overnight drive was extremely useful to get a better sense of how the car drove along my typical routes, and to get a sense of how charging worked both at home and at public charging stations.
If you can't decide after the first short test drive, don't hesitate to ask if you can schedule an overnight drive, it seems to be no problem getting one